early 14c., "noxious vapor in a coal mine, fire-damp, stifling poisonous gas," perhaps in Old English but there is no record of it. If not, probably from Middle Low German damp; ultimately in either case from Proto-Germanic *dampaz (source also of Old High German damph, German Dampf "vapor;" Old Norse dampi "dust"). Sense of "moist air, moisture, humidity" is not easily distinguished from the older sense but is certainly attested by 1706.

mid-15c., "to pursue, hound" (obsolete); 1530s, "to run, pass over," from course (n.). Related: Coursed; coursing.

late 14c., "to suffocate" (with or as with damp, foul air in a mine), from damp (n.). Figurative meaning "to check or retard the force or action of (the spirits, etc.)" is attested by 1540s. Meaning "to moisten" is recorded from 1670s. Century Dictionary (1897) states that "Dampen is now more common in the literal sense, and is sometimes used in the derived senses." Related: Damped; damping.

1580s, "dazed," from damp (n.). Meaning "slightly wet" is from 1706. Related: Damply; dampness.

c. 1300, "onward movement, motion forward, a running in a prescribed direction or over a prescribed distance; path or distance prescribed for a race, a race-course" from Old French cors "course; run, running; flow of a river" (12c.), from Latin cursus "a running; a journey; direction, track navigated by a ship; flow of a stream;" from curs- past participle stem of currere "to run" (from PIE root *kers- "to run").

Also from c. 1300 as "order, sequence;" meanings "habitual or ordinary procedure" (as in course of nature) and "way of life, personal behavior or conduct" are from early 14c.

Most of the extended senses developed 14c. from notion of "line in which something moves" (as in hold one's course) or "stage through which something must pass in its progress." Thus, via the meaning "series or succession in a specified or systematized order" (mid-14c.) comes the senses of "succession of prescribed acts intended to bring about a particular result" (c. 1600, as in course of treatment) and the academic meaning "planned series of study" (c. 1600; in French from 14c.), also "that part of a meal which is served at once and separately" (late 14c.).

Meaning "the flow of a stream of water" is from mid-14c.; that of "channel in which water flows" is from 1660s. Courses was used for the flow of bodily fluids and 'humors' from late 14c.; specifically of menstrual flux from 1560s.

Adverbial phrase of course "by consequence, in regular or natural order" is attested from 1540s, literally "of the ordinary course;" earlier in the same sense was bi cours (c. 1300). Matter of course "something to be expected" is by 1739.

"marsh gas," 1670s, from fire (n.) + damp (n.) "noxious vapor." Largely methane, it can spontaneously ignite when mixed with atmospheric air.

1764, "plot of ground laid out for horse racing," usually elliptical and with accommodations for participants and spectators, from race (n.1) + course (n.). Meaning "canal along which water is conveyed to or from a water wheel" is by 1841.

"in the middle of one's course," 1560s, from mid (adj.) + course (n.).

1630s, "to dull or deaden, make weak" (force, enthusiasm, ardor, etc.), from damp (adj.) + -en (1). Meaning "to moisten, make humid" is recorded from 1827. Related: Dampened; dampening.

"low spirits; dull, gloomy state of mind," 1520s, plural of dumpe "a fit of musing," of uncertain origin, possibly from Dutch domp "haze, mist," from Middle Dutch damp "vapor" (see damp (n.)). Compare vapors under vapor.

The application of this term to an affection of the mind is a part of the medical theory which attributed all disorders of the frame to a humour falling on the part affected, and regarded mental disorders especially as produced by a vapour rising from the stomach into the brain. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859]